JP2012182080A - Lead acid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead acid battery preventing stress generated due to stretch of an expanded grid in the vertical direction from concentrating to a root portion of an ear portion as a power collection portion.SOLUTION: The lead acid battery includes a battery case and an electrode plate formed by using the expanded grid which is arranged so as to be in contact with a rib provided on a bottom surface of the battery case. The electrode has an ear portion as a power collection portion on a top edge thereof and the rib provided on the bottom surface of the battery case is set to be deformed into a concave shape by stress capable of deforming the ear portion before the ear portion is deformed.

Description

  The present invention relates to a lead acid battery, particularly a lead acid battery for automobiles.

For lead-acid batteries, large current discharge is possible, and many paste type electrode plates with excellent productivity are used. The paste-type electrode plate is an electrode plate in which a paste-like active material is held on a lead alloy lattice. In lead storage batteries for automobiles and the like, from the viewpoint of improving productivity, an electrode plate in which a paste-like active material is held on an expanded lattice body obtained by cutting and stretching a lead alloy flat plate has come to be used. ing.
Since lead-acid batteries for automobiles are mounted in the engine room, they are exposed to high temperature environments due to radiant heat from bonnets, engines, etc., especially in midsummer. Corrosion of the grid of electrode plates proceeds when used at high temperatures. While the cast lattice has frame bones on both the left and right sides thereof, the expanded lattice body does not have the frame bones, and therefore, the expansion in the vertical direction due to the corrosion is large. On the other hand, the upper and lower dimensions of the electrode plate are regulated by abutting the lower side against the bottom of the battery case and welding the ear part as the current collector on the upper side to the strap. Therefore, the expansion of the expanded lattice body in the vertical direction is gradually increased by continuous use of the lead storage battery, and when the expanded lattice body is deformed, stress is concentrated on the base portion of the ear portion. Then, the possibility that the ear part is broken or broken at the base part of the ear part gradually increases.

  Such countermeasures to stress concentration at the base of the ear part in the expanded lattice body are shown in, for example, Patent Document 1, and a part of the electrode plate group of the bag placed at the bottom of the battery case is placed. The strength is partially weakened by cutting and thinning, and the stress is dispersed by deformation of the heel.

Japanese Utility Model Publication No. 02-079560

However, when the electrolyte (dilute sulfuric acid) adheres to the iron storage box of the battery, the bag described in Patent Document 1 corrodes the side surface of the iron storage box and pushes the side surface of the battery due to the volume change due to the generation of rust. Since the notch or the thin portion is arranged in the direction of absorbing the deformation when it is applied, it cannot be said that it is suitable as a shape that absorbs the deformation amount of the vertical extension of the electrode plate itself.
An object of the present invention is to provide a lead-acid battery that does not concentrate the stress generated by the vertical expansion of the expanded lattice at the base of the ear.

  In order to solve the above-mentioned problem, a first invention according to the present invention includes a battery case and an electrode plate of an expanded lattice body disposed so as to abut against a rib provided on the bottom surface of the battery case. Is a lead-acid battery that has an ear portion as a current collector on its upper side, and the rib provided on the bottom of the battery case is concavely deformed with a stress smaller than a stress sufficient to deform the ear portion. It is characterized by that.

  The second invention is characterized in that, in the first invention, the rib is made of a material that is more easily deformed than the bottom of the battery case.

  According to a third invention, in the first or second invention, the rib is composed of a rib body and a soft and elastic material fixed to the rib body.

  According to a fourth aspect, in the third aspect, the soft and elastic material is butyl rubber or ethylene propylene rubber.

  According to the present invention, the expansion of the expanded lattice body is absorbed by the concave deformation of the rib provided on the bottom of the battery case before the ear is deformed, and the ear is not deformed.

  If the rib is made of a material that is more easily deformed than the battery case bottom, the rib deformation prevents stress concentration on the ears, and the battery case bottom can be made harder to prevent external shock. On the other hand, a stronger lead-acid battery can be obtained.

  When the rib is made of a soft and elastic material with the rib main body, the bottom of the battery case and the rib main body can be integrally formed of a hard material, and the bottom of the electrode plate is soft and elastic. It can arrange | position so that it may contact | abut to the material which it has, and it can prevent the stress concentration to an ear | edge part with the material which is soft and elastic. Further, when the soft and elastic material is butyl rubber or ethylene propylene rubber, the elasticity can be maintained even when used in an electrolytic solution (dilute sulfuric acid) whose temperature has been increased by engine heat.

It is a figure which shows the electrode group used in one Example of this invention. It is a perspective view which shows the battery case used in one Example of this invention. It is a perspective view which shows the rib used in one Example of this invention. It is the perspective view which connected the strap to the electrode group used in one example of the present invention. 1 is an overall perspective view showing a lead storage battery which is an embodiment of the present invention. It is sectional drawing which shows the internal structure of the lead acid battery shown in FIG. It is a figure which shows an expanded lattice body.

<Battery>
The battery case described in the present invention accommodates a positive electrode plate, a negative electrode plate, and an electrode plate group constituted by a separator interposed between the two, and is easy to store the electrode plate group. A thing having a box body whose upper surface is opened and a lid body covering the upper surface of the box body can be suitably used. For the integration of the box and the lid, an adhesive, heat welding, ultrasonic welding, or the like can be used as appropriate.
The shape of the battery case is not particularly limited. However, since the electrode plate group is generally a rectangular parallelepiped, it is preferable to use a rectangular one so that the ineffective space is reduced when the electrodes are housed.
The material of the battery case is not particularly limited, but it must be resistant to the electrolytic solution (dilute sulfuric acid). Specifically, polypropylene, polyethylene, acrylonitrile-butadiene-styrene copolymer resin (ABS) or the like can be used. Polypropylene is advantageous in terms of acid resistance, workability (it is difficult to heat weld the battery case and the lid with ABS), and cost.

In addition, when the battery case is formed of the box body and the lid body described above, the box body and the lid body may be formed of different materials or the same material. It is preferable to use those having the same because no excessive stress is generated.
If necessary, the battery case can be provided with a safety valve. In a control valve type lead-acid battery, when an excessive charging current flows due to some trouble or the like, a safety valve is provided for releasing the internal pressure of the generated gas into the atmosphere.

<Plate using expanded grid>
As the electrode plate described in the present invention, an electrode plate using an expanded lattice is used.
First, a predetermined amount of Ca and Sn is dissolved in lead so as to have a predetermined alloy composition. A cast slab for positive electrode is produced by casting the lead alloy with a mold.
For example, the casting slab for positive electrode is continuously rolled until the thickness becomes 1.0 mm to produce a rolled sheet having a thickness of 1.0 mm and a width of 78 mm.
For the negative electrode, for example, a rolled sheet having a thickness of 0.6 mm and a width of 55 mm is produced in the same process.

  Next, slits in the longitudinal direction of the rolled sheet are sequentially put in a staggered manner in both the left and right regions excluding the central portion in the width direction of the rolled sheet, and developed in the width direction of the rolled sheet to form a mesh-like lattice. An expanded lattice body can be obtained by cutting this into a predetermined dimension and punching out the ears as the current collector from the non-deployed portion of the rolled sheet.

  This expanded lattice is filled with a paste-like active material kneaded with lead powder, required additives, dilute sulfuric acid and water, and is subjected to aging and drying to produce a positive electrode plate and a negative electrode plate.

<Production of battery>
The positive electrode plate and the negative electrode plate are alternately laminated via a separator to produce an electrode plate group having a structure of 6 positive electrodes / 7 negative electrodes. The electrode plate group was inserted into the battery case, the ears of the positive electrode plate and the ears of the negative electrode plate were welded, and the lid was placed on the battery case and welded to assemble the battery.
Dilute sulfuric acid was poured into the battery and left in a 40 ° C. water tank. Next, a direct current was applied to form a battery case. The battery was prepared by adjusting the electrolyte specific gravity of the battery after battery case formation to 1.280 (20 ° C. conversion).

<Concave deformation>
The concave deformation of the rib described in the present invention means that the rib provided on the battery case bottom is recessed downward. More specifically, it means that the rib itself is recessed downward, or the rib has a rib main body and an elastic body fixed to the rib main body, and the elastic body is recessed downward.
However, the concave portion is a case where a stress larger than a stress sufficient to deform the ear portion is generated on the ear portion of the expanded lattice, and in this case, the electric power is changed before the ear portion is deformed. The rib provided on the bottom of the tank is concavely deformed to prevent the ear from being deformed.
The amount of the concave deformation is not particularly limited, and depends on the vertical length of the expanded lattice body, but is approximately 1 to 3% of the vertical length, and the vertical length of the lattice body is 100 mm. If it is, it can be set to 1-3 mm.

<Rib>
The rib described in the present invention is provided on the inner bottom surface of the battery case, and the number thereof may be singular or plural, but the electrode plate using the expanded lattice described above is disposed on this rib. It is preferable to use a plurality. This is because the electrode plate can be placed stably.
The rib may be formed of a single material, or may have a structure including a rib main body and a soft and elastic material fixed to the rib main body. However, when forming with one material, it is necessary to change the material of the battery case bottom and the rib. When the rib main body and the soft and elastic material are used, the battery case and the rib main body are the same. Although it can be made of a material, it is necessary to later fix a soft and elastic material on the rib.

If the material of the rib is not soft and elastic, soft polyethylene or the like is used which is softer than the battery case and is concavely deformed with a stress smaller than enough to deform the ear portion. be able to.
When a soft and elastic material is used, polypropylene, polyethylene, ABS, or the like similar to the battery case described above can be used as the rib body. In particular, polypropylene is preferable in terms of acid resistance, processability, and cost.
As the soft and elastic material, butyl rubber or ethylene propylene rubber can be used. In particular, it is preferable to use ethylene propylene rubber because it easily absorbs stress.

The fixing of the soft and elastic material to the rib main body is not particularly limited, but a convex portion is provided on the upper surface of the rib main body, and the bottom surface of the soft and elastic material (the surface in contact with the rib main body) It can carry out by providing the recessed part fitted to the convex part of a rib main body, and making a convex part and a recessed part fit. In addition, a convex part and a recessed part can also reverse the rib main body which provides this, and the material which has soft elasticity. That is, a concave portion can be provided on the upper surface of the rib main body, and the convex portion can be provided on a soft and elastic material. Moreover, not only can a convex part and a recessed part fit simply, but it can also adhere using an adhesive agent.
Furthermore, it is not always necessary to use an adhesive. The soft and elastic material is pressed against the rib main body by the bottom side of the electrode plate placed thereon and does not fall off.

Embodiments of the present invention will be described below with reference to the drawings.
<Plate using expanded grid>
(Preparation of positive electrode plate)
A long rolled sheet made of a lead-calcium-tin alloy and having a thickness of 1.0 mm and a width of 78 mm is produced. Next, slits in the longitudinal direction of the rolled sheet are provided in both the left and right regions excluding the central portion in the width direction of the rolled sheet, and the unfolding process (expanding process) is performed in the width direction of the rolled sheet. The expanded lattice body 21 of FIG. 7 is produced by punching into a predetermined shape from the non-deployed portion of the sheet. As shown in FIG. 7, the expanded lattice body 21 includes a deployment portion 22, an upper frame bone 23, a lower frame bone 24, and ear portions 25 formed by the punching process. As described above, the expanded lattice body 21 has no frame bones at the left and right ends.
Next, water and dilute sulfuric acid are added to and kneaded with lead powder containing lead oxide as a main component to produce a paste active material for a positive electrode. This paste-like active material is filled in the expanded portion 22 of the expanded lattice 21, and the positive electrode plate 1 is produced through aging and drying.
(Preparation of negative electrode plate)
For the negative electrode plate, an expanded lattice is produced in the same process as the positive electrode plate.
Next, an additive (lignin, barium sulfate, carbon) is added to and mixed with lead powder mainly composed of lead oxide, and then water and dilute sulfuric acid are added and kneaded to obtain a paste active material for a negative electrode. Make it. This pasty active material is filled in the expanded portion of the expanded lattice body, and after aging and drying, the negative electrode plate 2 is produced.

(Production of electrode group)
The negative electrode plate 2 is inserted into a polyethylene separator 3 processed into a bag shape, and alternately combined with the positive electrode plate 1 to produce an electrode plate group 4 as shown in FIG. The electrode plate group 4 is composed of six positive electrode plates 1 and seven negative electrode plates 2, and both ends of the electrode plate group in the stacking direction are the negative electrode plates 2. In addition, although FIG. 1 has seen the electrode group 4 from the side surface, the ear | edge part 25 was abbreviate | omitting illustration.

<Example 1>
(Production of battery case)
The battery case material is polypropylene, and the battery case 5 as shown in FIG. 2 is produced using an injection molding machine. The outer dimensions are length: 230 mm, width: 170 mm, height: 200 mm, and the inside of the battery case is divided into six by partition walls 6. On the bottom surface of the battery case 5, two ribs 8 made of ethylene propylene rubber as shown in FIG. 3 are arranged for each portion partitioned by each partition wall. The rib 8 is integrally formed on the upper surface of the pedestal 7 by injection molding, and the pedestal 7 is arranged without being bonded to the battery case 5.
The height of the rib 8 is set to 8 mm together with the base 7, and the bottom surface of the electrode plate group 4 is lifted upward by 8 mm from the bottom surface of the battery case.

(Production of lead-acid battery)
The electrode plate group 4 described above has a voltage of 2 V, and a lead storage battery with a voltage of 12 V is configured by arranging six electrode plate groups in series.
The positive electrode plate 1 of the electrode plate group 4 and the ear portion 25 of the negative electrode plate 2 are each connected by forming a strap 9 as shown in FIG. 4 by a cast-on-strap (COS) method. Further, the battery case 5 described above is perforated at a partition wall portion corresponding to the strap 9 position of the electrode plate group 4. Six electrode plate groups 4 are inserted into the battery case 5, and the straps 9 are resistance-welded.
Thereafter, as shown in FIG. 5, the lid 10 made by injection molding and the battery case 5 are heat-welded using polypropylene as a material in the same manner as the battery case 5. The lid 10 is provided with a liquid inlet 11, injected with dilute sulfuric acid having a specific gravity of 1.230 (converted to 20 ° C.), energized with a direct current for a predetermined time, formed into a battery case, and a lead storage battery. Produced.

  FIG. 6 shows a cross-sectional view of the completed lead storage battery taken along the line AA in FIG. 5 (in the vicinity of the partition wall 6 in FIG. 2). As shown in FIG. 6, the electrode plate group 4 is held by the rib 8 so as to float from the inner bottom surface of the battery case 5, and the bottom surface of the electrode plate group 4 is in contact with only the rib 8.

<Comparative Example 1>
(Production of battery case)
The same thing as the battery case described in Example 1 was produced except that the rib on the inner bottom surface of the battery case was not provided and the height of the battery case was 190 mm.
(Production of lead-acid battery)
A lead storage battery of Comparative Example 1 was produced in the same manner as in Example 1 except that the battery case without ribs was used on the bottom surface. That is, Example 1 and Comparative Example 1 use the same electrode group.

(Evaluation)
Using the battery of Example 1 and Comparative Example 1, this was left in a 75 ° C. water tank, discharged at a discharge current of 25 A for 1 minute, and then 14.8 V and a limited current of 25 A. Performing voltage charging for 10 minutes is one cycle, and this is continuously performed for 610 cycles and left for 56 hours. After leaving, discharge is performed at a discharge current of 520 A for 30 seconds. If the voltage at 30 seconds is less than 7.2 V, the test is terminated. If the voltage is 7.2 V or more, the same test is repeated.
As a result, in Comparative Example 1, the base of the ear part was broken at 8540 times, and the life was reached.
In Example 1, the ribs deform and absorb the stress applied to the ears, so that the roots of the ears are not broken. However, by repeating charging and discharging, the expanded lattice of the positive electrode plate is corroded, and the lattice is expanded by volume expansion. Since the ear is fixed with a strap and the vicinity thereof is restrained from stretching, it deforms so that both end sides far from the ear of the upper frame bone warp upward, and comes into contact with the ear of the opposing negative electrode plate. The life reached 9760 times due to a short circuit between the plate and the negative electrode plate.
That is, in the present invention, the stress applied to the base of the ear can be reduced, and the life can be extended.

DESCRIPTION OF SYMBOLS 1 ... Positive electrode plate, 2 ... Negative electrode plate, 3 ... Separator, 4 ... Electrode board group, 5 ... Battery case, 6 ... Bulkhead, 7 ... Base, 8 ... Rib, 9 ... Strap, 10 ... Cover, 11 ... Injection hole .

Claims (4)

  A battery case and an electrode plate of an expanded grid body arranged so as to abut against a rib provided on the bottom surface of the battery case, the grid body having an ear portion as a current collector on its upper side, Lead acid battery configured such that the rib provided on the bottom of the tank is concavely deformed with a stress smaller than the stress sufficient to deform the ear portion.   2. The lead acid battery according to claim 1, wherein the rib is made of a material that is more elastically deformed than the bottom of the battery case.   The lead-acid battery according to the first or second invention, wherein the rib comprises a rib main body and a soft and elastic material fixed to the rib main body.   4. The lead acid battery according to claim 3, wherein the soft and elastic material is butyl rubber or ethylene propylene rubber.